When production intervals are completed in exploratory wells, it is common practice to "suspend" wells for a period of time to allow construction of pipelines and gathering facilities in conjuction with field development. In remote locations (offshore, e.g.), it may even be necessary to plug and abandon zones found productive until development wells can be drilled.
In many cases, it is not known how long a well may be suspended. Therefore, thorough measures are taken to isolate the productive interval from the surface. For example, following a flow test of the zone indicating productivity at commercial rates, the zone will be "killed" with completion fluid, a bridge plug set above the perforated interval, and a cement plug placed on top of the bridge plug. Two or three additional bridge plug/cement plug combinations may be placed above the interval to insure zone isolation during suspensin.
When the suspended well is re-entered to open the interval to production, the plugs must be drilled out. Frequently this results in substantial loss of drilling fluid to the zone. This is especially true if the zone was stimualted (fracturing or acidizing, e.g.) as part of the initial well test program. Once the plugs are drilled out, the zone is opened to production. Usually, a lower rate than the initial test rate is observed because of damage which occured during re-entry.
Thereofre, what is needed is a method which will allow a producing well to be "killed" and suspended without causing undue formation damage. Utilization of said method would result in maintaining the producing rate near that initially determined. Well re-entry costs would be reduced, and formation damage minimized.